Pat dry steak with a paper towel, place the steak in a freezer bag, and freeze for 30 minutes to firm it up.
Remove the meat from the freezer bag and thinly slice against the grain, transfer to a mixing bowl.
Marinate the meat with 2 tablespoons soy sauce, 1 teaspoon sugar, 1 teaspoon sesame oil, minced garlic, and a small handful of green onions, mix and marinate for 30 minutes.
Boil water in a large pot (1/2 to 2/3 full) and blanch spinach for 30 seconds. Use a slotted spoon to take the spinach out of the hot water and rinse under cold running water in a colander. Gently squeeze out excess water and transfer to a small bowl, add 1 teaspoon sesame oil, a pinch of salt, mix and set aside.
Add sweet potato noodles to the boiling water, stir, and cook for 7 minutes or until tender.
Drain and rinse the noodles in a large colander with cold water.
Use your hands to pick up a handful of noodles and cut the noodles so that they are about 12 inches long, place in a large mixing bowl.
Season the noodles with 1 tablespoon soy sauce, 1 teaspoon sesame oil, mix, and set aside (if allergic to sesame oil, use any allergy safe oil to prevent the noodles from sticking).
Preheat a wok or a large frying pan on medium high heat for a few minutes, the pan is ready when a small splash of water sizzles in the pan.
Add 1 teaspoon of olive oil in the pan and saute sliced onions until tender, add celery and saute 30 seconds more, set aside.
Add 1/2 teaspoon of olive oil in the pan and saute the carrot ribbons for 1-2 minutes until tender crisp, set aside.
Add 1/2 teaspoon of olive oil in the pan and add the beef into the pan, spread it out, and let the beef sear for a minute or two, then stir fry and cooked through, set aside.
Turn down the heat on the pan to low-medium, add 2 tablespoon soy sauce, 1 tablespoon sugar, and stir to dissolve sugar.
Add the noodles, meat, and vegetables to the pan and gently stir fry until thoroughly mixed.
Season to taste with additional soy sauce and drizzle with 1 teaspoon sesame oil, garnish with the rest of the scallions, and sesame seeds if using.
Serve as a main entree by itself or as a side dish.